Copper coated polybags improve seedling morphology for two nursery-grown Mexican pine species

Abstract

Root spiraling, root egression through drainage holes, and poor growing medium drainage are common problems in polybag seedling production systems in Mexico. Two commercially and environmentally important Mexican conifer species, Pinus pseudostrobus Lindi. and Pinus montezumae Lamb., were grown in simulated Mexican “platabanda” nursery conditions. The seedlings were grown in polybag containers, with and without chemical root pruning and with six different drainage designs. A chemical root pruning product, Spin Out ®, was evaluated on these two pine species. Six different drainage designs ranging from an open-bottom, well-drained design, to small holes and restricted drainage were tested. The results clearly demonstrated benefits from the chemical root pruning, but the impact of the drainage treatments was distorted by the use of a well-drained growing medium. Root collar diameter, shoot dry weight, and root dry weight were increased in Spin Out ®-treated seedlings. These seedlings also had significantly fewer roots egressing from the bag and spiraling at the bottom of the polybag. Generally, Spin Out ®-treated seedlings had a more fibrous and well-developed root system than untreated seedlings. Chemical root pruning can be used to reduce or eliminate root deformations and improve seedling quality of these two Mexican pines.